There is presently known in the prior art a single-cylinder, truck mounted brake rigging, as shown for example in U.S. Pat. Nos. 4,613,016 and 5,069,312 which have been designed for use with truss-type brake beams. In this respect, the braking force applied through the rigging acts on the respective brake beams at the beam midpoint where maximum resistance to bending forces is effective by reason of the beam strut arm transferring the load between the beam compression and tension members. Such a single-cylinder rigging, when combined with truss-types brake beams, is believed to offer maximum efficiency of operation at a relatively low cost.
A typical single-cylinder, truck mounted brake rigging generally comprises a pair of spaced apart brake beams having brake heads at each end thereof, a pair of transfer levers pivotally connected at a point intermediate the ends thereof to a respective one of the pair of spaced apart brake beams, and a pair of force-transmitting means, one of which includes a brake actuator means and the other of which typically includes a slack adjuster mechanism, connecting the pair of transfer levers so as to form a brake beam interacting linkage which causes the application of the brake heads to the wheels of the railway vehicle. This braking system is a freely suspended system that fits most standard trucks with combination bolsters, and requires no special bolsters or connections of any kind to existing bolsters or car body. As shown in FIG. 2, the single-cylinder, truck mounted braking system is designed such that the force transmitting members extend through openings in the bolster portion of the truck.
Some of the newer truck designs interfere with the slack adjuster force transmitting member at the location where the slack adjuster extends through the openings in the bolster portion of the truck. This interference causes undesirable rubbing of the slack adjuster against the bolster bowl area of the truck.